Electronic programme-control



A ril 27, 1965 J. LOSCH ET AL ELECTRONIC PROGRAMME-CONTROL Filed Nov. '25, 1958 Fig.1

Data Data Data Handling Handling Handling Unit Unit Unit pl 12; .p2 ""1 pm Gating /sl l/ l I 1 I I Central Electronic n ,Gating Processing Station Selector F 19.2 Dz/ta Ulla DJta Handling Handling Handling Unit Unit Umt L ..P1 I p im% L/rm r1 r2-i pm 'L L J 1 n1 R\T $1 1 AS 'Line Finder l ZVA PW N1 D2 a m I l i Centrql Electronic ,1 Processing e Station Selector ""9 P P INVENTOR.

J. L'O'SCH H. ZSCHEKEL ATTORNEY April 7, 1965 J. LCSCH ETAL 3,181,121

ELECTRONIC PROGRAMME-CONTROL Filed Nov. 25, 1958 3 Sheets-Sheet 2 Data Handling Data Unir mg m m 0R GATE INVERTER g 3:

Z(counrer) & am

, Line Finder Central Station Selector PI p22 p23 p gm Z VA PW &

F 3 Y 02 G r{ g P INVENTOR. J. Lb'scH H. ZSCHEKEL April 1965 J. LbscH ETAL 3,181,121

ELECTRONIC PROGRAMME-CONTROL Filed Nov. 25, 1958 3 Sheets-Sheet 5 Fig. 4

Counter pel pa? p23 pl pen p 23 l Gpm2 Gating INVENTOR. J. L'o'sci-i H. ASCHEKEL ATTORNEY United States Patent 3,181,121 ELECTRONIC PRGGRMW-CGNTROL .liirgen Ltisch and Hans Zsehelrel, Stuttgart, Germany,

assignors to international Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Nov. 25, 1958, Ser. No. 776,231 Claims priority, application Germany, Dec. 12, 1957, 13,256/57 9 (til. sec-147 This invention relates to an electronic programme-control for data-processing systems comprising a central processing-station, such as an electronic computing, bookingor sorting-unit, to which several inputand output-units are connected. In such kinds of systems the central processing-station generally consists of a number of structural units which are more or less independent, such as storages, highspeed storages, computingseating-stages, and the like, which are connected together or in individual groups for accomplishing diiferent results.

In conventional types of electronic computing and booking systems, pluggable programmes may be provided, permitting certain programmes to be plugged in for carrying out specific sequences of operations. Thus, with respect to the stock-on-hand supervision the recording of received goods is of interest on the one hand, and, on the other hand, the recording of the stcck-onhand at certain times. In accordance with the present state of the art and for carrying out these and other operations, a computing system is set manually for a certain time to the programme recording of received goods or to the programme recording of outgoing goods, or to the programme of printing issue vouchers, and a greater number of operations are processed for whichever programme the system is set. In accordance with another conventional solution, provision is made to produce first of all from each process record means, preferably punched cards or perforated tapes, on which the respectively desired processing-programme is characterized by control marks, which record means are then processed in accordance with the programme, as indicated by the control marks. In either case, and on account of manually released programme controls, or by the time required for producing the record means, time delays appear between the availability of the information and its processing, and it is impossible to immediately process the informations directly upon receipt and in the order of succession of the reception.

In order to avoid frequent and time-wasting changes of the programme, certain operating conditions have to be adhered to in such a system, e.g. performance of recordings regarding outgoing goods during the normal busimess-hours, and the performance of stock-keeping corrections by recording the incoming goods, as well as the listing-out of the stock figures outside the regular working time.

From the above described example it will be see that in systems with fixed programmes, a really economical utilization of the equipment can only be accomplished when the same programmes can be maintained throughout longer periods of time.

With respect to computing systems, the conditions differ in so far as frequent changes of the programme are necessary. For this reason, in high-speed computing systems, instead of a control of the prograrmne by means of pluggable programmes, a controlling by means of individual orders or instructions, or successions thereof has been provided. In this case the individual information Which is supposed to be processed Within one operating cycle of the machine is preceded by an instruction which is either fed in together with this information, or is being called up on account of an instruction number from a special instruction storage device (programme storage). Such an instruction-controlled programme is suitable above all whenever long-lasting computing operations, for instance, scientific calculations are concerned. In this case a plurality of computing operations has to be repeated in a routine manner in the order of sequence, as given by the list of instructions, and the majority of the intermediate results is further processed within the machine itself, whereas only a small portion of the obtained results is fed out via a list-printer or any other outputunit at the end of the computing programme. For this reason also the number of inputand output-units which are provided in electronic computers, is relatively small.

The present invention is based on the problem of providing, for data-processing systems employing a highspeed electronic processing unit, an automatic programmecontrol permitting a cooperation of this central processing station with a plurality of more or less slow-operating inputand output-units of diiierent types, even in the case of a frequent change in programme corresponding to the the different types of units.

The object of the present invention is to provide an electronic programme-control for use in data-processing systems employing a central processing station and a plurality of different inputand output-units capable of being connected with this central station via gating means and corresponding information-transrnission leads, in particular for employment with computing, readin and booking-systems.

According to the invention this electronic programmecontrol of data-"processing systems is arranged in such way that control leads are assigned to each inputand output-unit indicating to the central processing station, by means of marking potentials, the respectively required programme, as well as the state of being ready for operation of the respective unit, and so that the marking potentials are only applied to an electronic progranmieselector after the information or control leads have been connected through to the central processing station, and so that, via this electronic programme-selector, the central processing station is switched over to the indicated programme by the action of electronically controlled switches. Preferably a special call line is assigned to each respective inpu or output-unit for indicating the ready-to-operate condition, as well as one or more programme control leads for selecting the programme, and furthermore the arrangement is made in such a Way that the gating means are connected with a line finder which is adapted to effect a cyclical scanning of the call lines and which is rendered inoperative via the first call line conducting a marking potential, until the programme corresponding to this call line and the control line which is assigned thereto is called up in the central processing station. In a variation, the special call or unit ready lines can be omitted and their function usurped by the programme call lines.

The automatic programme-control, according to the invention, has the great advantage that, in cases Where a high-speed electronic processing unit cooperates with a plurality of inputand output-units of the same or of a different type, which are actually mostly rather slow with respect to their operation, due to their mechanical or electromechanical component par-ts, and, accordingly, with the same or differentin-formation processing programmes, complete utilization of the operating capacity of the central processing station is obtained. In the following, further advantages and features of the invention will now be described with reterence to the accompanying drawings, in which:

PEG. 1 shows an elemental block diagram for the system involving an electronic programme-control,

FIG. 2 shows a block diagram of the system embnacing :he main or preferred embodiment of the invention involv-ing control of the gating means and the electronic programme-selector via unit-ready lines, programme call lines and line finder, V

FIG. 3 shows a basic circuit diagram for the line finders and the gating means for information-transmission and control leads in their preferred arrangement schematically indicated in FIG. 2, and

FIG. .4 shows a basic circuit diagram relating to the variation in which the function of the unit-ready lines in controlling the line finder is usurped by the programme call or control leads.

In FIG. 1 there is shown a block diagram for dataprocessing systems employing an electronicprogrammecontrol. The central data processing station ZVA and m data handling units; that is respective data input or output-units 1, 2, m, are connected with each other on the one hand, via information-transmission lines i and, on the other hand, via programme call or control leads 2. For reasons of simplicity, only one line i and one line p have been shown in FIG. 1 for each respective inputor output-unit. However, in the case of different types of inputand output-units several iand p-lines per unit may also be provided. For reasons of clarity the iand o-lin'es of all inputand output-units are shown assembled to form respectively a cable I and a cable P.

The cable I is terminated in a gating arrangement D1 selectively permitting the connection from any one of the at respective inputor output-units to the central prowss- ,ng station ZVA. The cable P is terminated in a'gating lrr'angement D2, permitting the connection of one of the programme call or control leads p with one of the n input .ines pe.

The input lines pe are connected with an electronic grogra-mme-seiector PW and enable the selection of n :liiferent programmes. Via the output lines pa, the eleclIOIllC programme-selector is connected with the central processing station ZVA.. Via these output lines, the elecronic programmeselector controls the sequence of func- :ions in the central processing station in accordance with :he programme as selected by marking one of the 12 input mes.

For permitting the application of the marking potentials the electronic programme-selector only after the information-transmission lines have been connected to the cenral processing station, the gating arrangements D1 and D2 are connected with each other via control leads S. As a rulethe number of these control leads is at least :qual to the number of respective inputor output-units, 2r respectively corresponds to the number of different :ypes of these units.

In the above described elemental embodiment the pro-.

gramme-lines p, also referred to as programme'call or )rogramme control lines or leads, are adapted to, perform wo different functions. On the one hand, they indicate he ready-to-operate condition of the respective inputor )utput-units and, on the. other hand, they are adapted to :ontrol the programme-selection. In order to simplify he circuit arrangement of the respective gating means D1 )1 D2, it is appropriate to separate these two functions 1nd to provide special call lines for indicating the readyo-operate condition. In FIG. 2 there is shown a correzponding block diagram of a system incorporating the nain or preferred embodiment of the invention. In ac- :ordance With theshowing of FIG. 2, one call line r is lssigned to each of the m respective input or output-units, vhich call line is indicated by a dashline. The call lines of all inputor output-units are shown assembled to orm a cable R which is connected with a line finder AS. fhis line finder is adapted to control the gating means )1 and D2 via control leads S1 and S2, respectively.

Apparatus further exemplifying the main embodiment if the invention, diagrammed in FIG. 2, is shown in' IG. 3. This FIG. 3 shows a detailed basic circuit diagram relating to the gating arrangement D1 and D2, as well as the line finder AS. For making the construction of the gating arrangement D1 as simple as possible it has been assumed that only one information-transmission line has been assigned to each of the inputand output-units, on which line individual bits of binary-coded information are transmitted in series. It is to be understood, however, that the expression information transmission line (i) or the like is to have a broad connotation also covering a multi-Wire channel for the concurrent transmission of item coding bits and that a single line and connected gate as shown may represent a multi-wire channel and corresponding multiple gating. Similar broad meaning is to be accorded the terms unit-ready or call line (r) and programmecall line .(p)

As shown in the FIG. 3 embodiment, the informationtransmission line i3, as well as the call line r3 and the programme line 23 are assigned to the input-unit 3. The information-transmission.line i4, .the call line 14 as well as three programme lines p4 p4 and p4 are assigned to the input unit 4.

The differences relating to the different programmes which are capable of being selected via the programme lines p4 through p4 will be described hereinafter in connection with an example of practical application.

As will be seen from the showing of FIG. 3, the cable I is connectedwith the gating-arrangement D1. The individual information-transmission lines il-im are respectively applied to the associating gating circuits Gil through Gim, each information transmission line to one of the inputs of the associated gating circuit. The information input-gates are designed as AND-gates. The outputs of the information input-gates are connected with a bus bar d1 which is adapted to feed the information applied via any of the information input-gates to the central processing unit ZVA.

The call lines r of all data-handling inputand outputunits are connected with the line finder AS. In this line finder one call gate Gr is assigned to each of the call lines r. For instance, the call line :1 is connected with one input of the gate Grl, etc., and the call line rm with one input of the gate Grm. The call gates are likewise designed as AND-gates. The outputs thereof are connected respectively with the second inputs of the information input-gates Gil through Gim via the corresponding control leads s1 through sm.

For effecting the cyclical scanning of the ready-t0- operate indication by the call lines a counter Z is provided in the line finder comprising a number of stages Z1, Z2 through Zm corresponding to the number of respective inputor output-units, the outputs of said counting stages being respectively connected with the second inputs of the corresponding call gates Grl arm. The corresponding information-transmission path will only be connected from the respective input unit to the central processing station in the event of a coincidence of both the counter position and the ready-to-operate indication on the call line. 7

For example, if the call line r2 is marked or indexed with a call indicating potential, and if the counter assumes the position Z2, then the call gate Gr2 will be opened and its output .92 will accordingly also be excited, thus unblocking the information input-gate Gi2.

By this unblocking of the information input-gate Gi2 the operating resistance which is connected to the information line i2 will be varied. This variationof the operating resistance may be utilized for reading the information from the input-unit 2. However, as shown in FIG. 3, there may also be provided an information-reading line a2 which is connected to the output ofGrZ, and which is furthermore connected with the associating input-unit 2. In FIG. 3, by way of example, the information-reading line ad for the input-unit 4 is excitedupon operation of the call gate Gr 4 (not shown) associated therewith to notify or condition this input-unit to read or apply information bits to the associated reading gate 61'. For simplifying the representation, the information-reading line a1 through am are shown to be gathered into one cable A.

Furthermore it is assumed that the inputor outputunits are so desi ned that the marking of their call line will be disconnected after the respectively selected programme has been carried out. if so required, this disconnection may also be effected by the central processing station by means of indication End of lrogramme which is transmitted via a special line.

After the programme has been carried out with respect to one certain inputor output-unit the counter'Z may be stepped on until it detects the next successive inputor output-unit which is ready to operate. To this end there is provided in the line finder AS a pulse-generator G which, via an AND-gate Ge, feezs stepping pulses to the counter Z Whenever Ge is unblocked. The second input of Ge is indirectly controlled by the call lines r, that is, via the call gates and the control leads s1 through sm. These control leads are individually connected with the inputs or" an (DR-gate Oz which is unblocked when one of the control leads is energized. The output of the OR-gate Gz is connected via an inverter U with one input of Ge. in the conventional manner the inverter U operates in such a way that its output is energized whenever its input is not energized, and vice versa. By means of this, and as long as one of the control eads is energized, the input of U will be energized via Oz and, consequently, Ge will be locked. Assuming, for instance, that the control lea s2 is energized so that correspondingly the in ut-unit 2 is connected and conditioned for transmission of data to the entral processing station, then Ge is blocked and the counter is prevented from being stepped on until the programme which is desired by the input-unit 2 has been completely carried out.

After this programme has been carried out, the marking or" the call line r2. will be discontinued and, consequently, (3P2 will be blocked, so that now the control lead 52 is no longer energized. As long as the counter Z still remains in the position Z2, also none of the other control leads can be energized. On account of none of the leads s being energized, the OR gate Oz will not be energized, the input of U Will not be energized and, via the output of U, the gate Ge will be unblocked, so that now stepping pulses will be transmitted from the generator G to the counter Z, and the counter will be stepped on until, in the event of a coincidence of both the counter position and tire marking of the matching call line r, a new control lead s will be energized. This control lead,

being energized will then, in the manner described, suppress the further application of stepping pulses; hence the counter Z will stay in its new position until the marking potential on the matching call line 1- is removed.

The controlling of the line finder AS by the call lines r has been described above, as well as the cooperation of the line finder with the gating arrangement D1 for the "ansmission or" information from the data handling units to the data processing means ZVA. In the following the connecting-through of the programme lines p within the gating arrangement 32 to the electronic programme selector rW will now be described. For the connecting through of the programme lines p, a number or" AND- gates Gpi. through GpmZ is provided in the arrangement D2. corresponding to the number of programme lines. One input of each of these AND-gates is connected with the respective associated programme line. In EEG. 3 the programme lines p1, p21, p22, p23, pml, pmZ are shown conforming to the assumption that only one programme line is assigned to the input-unit 1, three programme lines to the input-unit 2, and two programme lines to the input-unit The connection of the programme lines p to the input lines pe of the electronic programme-selector PW is effected by gates Gp under the control of the counter Z of the line finder AS. The outputs of the counter stages zl through zm are connected via corresponding control leads spl through spm with the AND-gates in the arrangement D2. Since, as already mentioned in the foregoing,

only one programme line pl is provided for the input unit 1, the control lead cpl only leads to the gate Gpl.

With respect to the input-unit 2, three programme lines the arrangement D2 will condition the gates o zr through GpZE": for response to the energization or marking of programme call lines p21, p22. and p23 of the data handling unit 2. In the data handling input-unit 2, suppose that the programme line 222 has been marked. Thereupon, and via GpZZ, in the example according to FIG. 3, the input linepeii of the electronic programme-selector will be energized. By means of the line ps3 the programme with the number 3 will be selected.

T. e control leads spll through spm mayalso be connected to the control leads sll through rm and not, asin the described example of embodiment, to the outputs 21 through zm' of the counter. This bears the advantage that additional component parts which are not shown in FIG. 3-for suppressing momentary markings of the input lines pc can be avoided.

The outputs of Gp gates may be variously wired to the input lines pe, as by plug wires K. As indicated in FIG. 3, the'outputs of GpZZ and Gpml are both wired to input line pe3;'hence the input line pe3 may also be selected by the input-unit m by marking the programme line pml via the gate Gpml. Altogether it is assumed in the above mentioned example that the electronic programme-selector is designed for the selection of it different programmes. Accordingly, the gating arrangement D2 is provided with n outputs. The programme lines p are applied to the input side of D2, the number of lines being at least equal to the number of the inputand output-units. In most cases the number of programme lines p is substantially greater, because the inputand output-units respectively require several programmes.

It is still to be mentioned that in the gating arrangement D1, the gates Gil, Gi2 and Gim, which are shown in FIG. 3, are indicated as information input-gates. Accordingly, the data handling units 1, 2, 3, 4 to mare input-units. Whenever the data handling units to be connected are output units, then the corresponding AND- gates in the arrangement D1 will have to be connected as information output-gates, in other words, in the reversed forward-direction. If inputor output-units are each to be connected with the central processing station by means of several information-transmission lines, then, for

each of these lines as well as for every desired'forwarddirection (pass-direction), a corresponding AND-gate will have to be provided which is to be unblocked by the associating control lead s in dependence upon the. position of the counter and the marking of the call lines r.

Up to now it has been presupposed that the indication as to the ready-to-operate state is efiected via special call lines r. However, with respect to the casein which the programme lines p in both the inputand output-units are only marked when these units and already ready to operate, the controlling of the line finder may also be eifected via the programme lines themselves. In FIG. 4 of the drawings there is showna variation of the FIG. 3 embodiment or" the invention. In this variation, the gates Gr of as weL as by the counter stages 21 to zm.

In the example shown in FIG. 4, programme line p1 (from input unit 1-FIG. 3) has a branch connection 01 .to an input of the gate Grl, the three programme lines p21, p22 and p23 of the input-unit 2 are connected with the three inputs of the OR-gate O2, and the two programme lines pml and 12/112 of the input-unit m connect with the two inputs of the OR-gate Om. The outputs 0t these OR-gates,-in pairs with the outputs of the corresponding counting stages, constitute the inputs of the associated call gates G22 and Grm. Thus in each instance where only a single programme line comes from an input unit, this line will be connected directly to the proper call gate Gr whereas in every case where a plurality of programme lines come from-an input unit, the plurality of programme lineswill connect through an OR gate to the call gate Gr for the input unit. If, for instance, in the input unit 2 the programme line p22 is marked, then the gate 02 will be unblocked, the output thereof being connected via the line oZwith the one input of GrZ. If

new the counter Z assumes the position 2:2, then Gr2 will be unblocked and the control lead s2 will be energized, and via s2 the connection of the information-transmission path will be etfected. Concurrently, via the control lead Sp2 and the gate Gp22, and in connection with the'marking of the programme line 222, the input line p123 of the electronic programme-selector will be energized, thus selecting programme number 3.

The arrangement of the line finder as well as of the various gates in the gating arrangements chiefly depends on the different types of inputand output-units. For example, if these units are magnetic storage devices, it will be appropriate to employ electronic switches as controllable switches in the line finder within the gating arrangements and in the electronic programme-selector. However, if-the central processing station is supposed to cooperate with electromechanical inputand output-units, then it is preferable to employ as controllable switches of the electromechanical type, such as telegraph relays.

From theabove mentoned exemplified embodiments it will be seen that the automatic programme control enables a cooperation of the central processing station with a plurality of inputand output-units. The advantages of a data processing system designed in accordance with this invention will become particularly evident in cases where the time required for an input unit to provide data for processing and to achieve a ready-to-transmit condition is substantially longer than the processing time itself.

Such a relationship with respect to time will always exist when the data are fed in by hand, e.g. in the above mentioned example relating to the recording of incoming and outgoing goods. Such operations occurin an arbitrary order of succession and require different programmes.

For each recording or booking operation, the respective item or list number has to be fed in as well as the piece number. When feeding in this data via a keyboard several seconds are required. The processing of the feed-in data within an electronic booking system, however,.o nly requires a few milliseconds. On account of the electronic programme control the central, booking system is now in position to deal with a great number of input-units which are operated, in parallel by several operators. In this 1 case it is appropriate to feed the information to be processed to the input-units at first, i.e. in the presentexarn stock figuresrelating to the respective itemrto the input operators position.

In many cases of practical application a fixed assignment exists between a certain type of input device and a certain type of output device. Thus, it is possible,.in an automatic booking system and on account of an exist ing order, to couple the item-to-price translation to the booking operation relating to the recording of outgoing goods. In this case it is appropriate to provide one common programme line for the combined inputand output-unit corresponding to this translation.

A programme control according to the invention may also be employed in a data processing system comprising severalprocessing units'serving difierent functions. In such a case it is appropriate to'arrange the programming circuit in such away that the call orprogramme lines control a selector for processing units.

If the data processing system is supposed to cooperate with input devices for evaluating mechanically readable information record means, then the programme lines are advantageously marsed via an evaluating circuit for instruction signals.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forthin the objects thereof and in the accompanying claims.

What is claimed is:

1. Computing apparatus or the like, comprising a plurality of data handling units, each with a data transmis sion line and with at least one programme line, data processing means common to said units for carrying out directed programs of data processing operations, first gatine means conditionable' to connect the data transmis sion lines of the data handling units selectively with the data processing means, program selecting means for directing the data processing means to carry out selected programs as called for by marked programme lines of the units connected by said first gating means,,second gating means conditionable to apply theeflect of marked programme lines of the data handling units selectively to the.

program selecting means to operate the latter for selecting the program for the data processing means, unit selecting means for concomitantly conditioning the first and second gating means respectively to connect the transmission line of only one selected data handling unit at a time to the data processing means and to apply the effect of a marked programme line of this same unit to the program selecting means and means coupled to said data handling units for conditioning said unit selecting means.

2. Apparatus according to'claim 1, the second gating means including .AND gates, one for each programme line, each gate having one input connected with the related programme line and another input connected with said unit selecting means so as to be effective upon concurrent marking of its inputs by, the programme line and the unit selecting means to apply program selecting potential'to the program selecting means.

3. Apparatus as in claim 1, the data handling units including input units with transmission lines energizable to manifest data for transmission to the data processing means, said first gating means including AND gates havmeans and energizable to signal the unit selecting means of the readiness of the'data handling unit to be selectedfor connection of its transmission line through thefirst gating means with the data processing means and for connection of its programme line through the second gating means:

with the program selecting means.

5. Apparatus as in clan-n4, the unit selecting means including a line finding counter having successive unit selecting positions, means for stepping the counter from one position to the next to scan the call line of one data handling unit after another, and means operable under control of the counter and the first call line found thereby to be energized for interrupting stepping of the counter at a position for selecting the data handling unit related to the controlling call line.

6. Apparatus as in claim 1, the unit selecting means including a line finding device having successive positions corresponding to diiferent ones of the data handling units, means for stepping the device from position to position to scan the units for ready signals, and means controlled by the device and first ready signal encountered upon scanning for effecting the conditioning of said first gating means to connect the data processing means to the trans mission line of the data handling unit responsible for the controlling ready signal.

7. Apparatus as in claim 6, the means controlled by the device and ready signal also interrupting stepping of the device to maintain the device in the position corresponding to the data handling device responsible for the controlling ready signal until this signal is withdrawn.

8. Apparatus as in claim 7, said ready signals being obtained from the data handling units through their programme lines when marked.

9. Apparatus as in claim 8, some of the data handling units being provided with a plurality of programme lines, and an OR gate operated by marking of any of the plurality of programme lines of a data handling unit for producing the ready signal for this unit.

Reierenees Cited by the Examiner OTHER REFERENCES Keister et al.: The Design of Switching Circuits, N.Y., Van Nostrand, 1951, pages 327343 relied on.

NEIL C. READ, Primary Examiner.

IRVING L. SAGROW, EVERETT R.

REYNOLDS, ROBERT H. ROSE, Examiners. 

1. COMPUTING APPARATUS OR THE LIKE, COMPRISING A PLURALITY OF DATA HANDLING UNITS, EACH WITH A DATA TRANSMISSION LINE AND WITH AT LEAST ONE PROGRAMME LINE, DATA PROCESSING MEANS COMMON TO SAID UNITS FOR CARRYING OUT DIRECTED PROGRAMS OF DATA PROCESSING OPERATIONS, FIRST GATING MEANS CONDITIONABLE TO CONNECT THE DATA TRANSMISSION LINES OF THE DATA HANDLING UNITS SELECTIVELY WITH THE DATA PROCESSING MEANS, PROGRAM SELECTING MEANS FOR DIRECTING THE DATA PROCESSING MEANS TO CARRY OUT SELECTED PROGRAMS AS CALLED FOR BY MARKED PROGRAMME LINES OF THE UNITS CONNECTED BY SAID FIRST GATING MEANS, SECOND GATING MEANS CONDITIONABLE TO APPLY THE EFFECT OF MARKED PRO- 